Fuel igniter for a jet turbine engine afterburner



E. BADER May 9, 1967 FUEL IGNITER FOR A JET TURBINE ENGINE AFTERBURNER Filed July 9, 1965 AFTERBURNER COMBUSTION CHAMBER MAIN FUEL MAIN FUEL NOZZLE HIGH PRESSURE 5c PUMP NOZZLE LOW PRESSURE IGNITING FUEL JET 8a ow PRESSURE FUEL 7 AFTERBURNER 9? PILOT DA 5 E m@% Z w W MN I M. 0 MW v? 5/ United States Patent Ofiice 3,318,091 FUEL IGNTTER FOR A JET TURBINE ENGINE AFTERBURNER Eberhard Bader, Stuttgart-Mohringen, Germany, assignor, by mesne assignments, to Man-Turbo G.n1.b.H., Munich, Germany Filed July 9, 1965, Ser. No. 470,764 Claims priority, application Germany, July 15, 1964, M 61,729 1 Claim. (Cl. 60-39.82)

This invention relates to a mechanism for the distribution of fuel to the ignition zone in the afterburner of a turbine jet engine. In particular, it is directed to the means for supplying the fuel to the afterburner and igniting the fuel.

Devices exist for supplying and igniting fuel for the afterburner of a turbine jet engine in which two fuel jets are used. The first flame is produced from the liquid fuel which is introduced through a nozzle located .in the engine combustion chamber in advance of the turbine. The flame thus formed shoots through the turbine in order to ignite the liquid fuel which has been introduced through a nozzle which has been located in the afterburner to the rear of the turbine. This second fuel jet ignites the afterburner fuel which continues to burn automatically after the first and second igniting fuel jets have been extinguished.

Such fuel ignition system has the problem of the correct metering of the quantity of fuel for each of the two fuel nozzles. The first fuel jet must burn long enough and at such intensity that it can ignite the fuel introduced through the second nozzle in the afterburner. However, it must not burn at such an intensity and long enough to burn the turbine wheel. Also, it must be assured that the fuel is discharged at an exact time through the second nozzle in the afterburner.

The object of this invention is to produce means for providing fuel through the nozzle in the engine combustion chamber as well as to the nozzle in the afterburner in the required amount and at the right time, and then to positively stop the supply of fuel when it is no longer needed to ignite the afterburner.

In general, these objects are produced by an apparatus which supplies fuel through two nozzles, one of which is mounted in the engine combustion chamber in advance of the turbine for forming a flame which shoots through the turbine and a second nozzle arranged to the rear of the turbine adjacent the afterburner in order to form a second flame which is ignited by the flame coming through the turbine and which, in turn, ignites the afterburner.

In this invention, the distribution of the fuelto the first nozzle in the engine combustion chamber and to the second nozzle to the rear of the turbine is controlled by a single element which supplies fuel to the engine combustion chamber for the first flame only after the amount of fuel necessary for the formation of the second flame adjacent the combustion engine has been introduced through the second nozzle. The supply of fuel to each nozzle is positively shut off after the first and second flames have been formed in the afterburner.

The control element of this invention is composed of a piston slidably mounted in a cylinder and which pumps fuel in the cylinder through a valve to the second nozzle to the rear of the turbine and pumps another portion of fuel to the first nozzle in the engine combustion chamber through a bore in the piston skirt, a circumferential groove in the skirt, and a valve in the wall of the cylinder.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying drawings, in which:

FIGURE 1 is a longitudinal cross-sectional view of the fuel pump when the cylinder is full of fuel; and

3,318,091 Patented May 9, 1967 FIGURE 2 is a similar view but showing the piston at the end of its fuel discharge stroke.

The housing 1 is composed of several different parts, one of which contains a cylinder 2. Piston 3 is slidably mounted in the cylinder and is urged in its intake stroke position by spring 4. Discharge check valve 5 in the end of the cylinder toward a first side of piston 3 opens outwardly for discharging fuel into the pipe line 5a leading to a nozzle 5b in the ignition zone of the afterburner 5c in the jet tube and behind the turbine St! in the engine. The intake valve 6 opens into the cylinder 2 and is joined to the low pressure fuel line 100. Check valve 7 opens outwardly and is connected to low pressure line 100. Check valve 8 located in the cylinder wall opens outwardly and is connected to a pipe line 8a extending to a fuel nozzle 8b in the engine combustion chamber 80. On a second side of the piston 3 and aligned with the cylinder 2 is a second cylinder 9 containing an axially movable piston 10. This piston is connected by a valve stem to a valve head 11 directed toward cylinder 2 and on the other side to a piston rod 12 joined to a control piston 13 mounted in cylinder 14. Piston 13 is urged in a direction to close valve 11 by means of spring 15. On the other hand, hydraulic pressure is applied to the other side of the piston 13 through bore 16 to open valve 11. Cylinder 9 communicates with cylinder 2 through passage 17 and through passage 18 is joined to the low pressure fuel line 100. Passage 19 is connected to the high pressure fuel line 200 and to chamber 20 in housing 1. Passage 21 connects chamber 20 with cylinder 2 on the second side of piston 3 and opposed to spring 4. B-ores 22 and 24 in the cylinder wall and bore 23 in the piston provide communication between passage 19 and cylinder 2 for the flow of cooling liquid.

The control mechanism starts with a cylinder a having a piston b. Chamber 0 in the cylinder is connected through a bore d and line e to high pressure line 200. To actuate the afterburner, lever f, which is joined by connecting rod g to piston b, is moved in the direction of the arrow so that piston b opens bore h, piston b having moved to the shaded position, so that cylinder :1 is connected to port 16 by line i. Piston 13 is thus moved to the right. When piston b is returned to starting position, flow to port 16 is stopped, piston 13 is urged to the left by spring 15, and the fuel leaks by connecting rod 12 into cylinder 9 and thus to the low pressure line 100.

The flow of the cooling liquid takes place as follows. If the afterburner is not ignited, then a small amount of fuel flows constantly from high pressure line 200 through bore 22, bore 24, passages 17 and 18 to low pressure line 100, as well as by passage 24a at the end of cylinder projection 24c, and from there through bore 23 in piston 3 into cylinder 2 and valve 6 to low pressure line 100.

When the afterburner is actuated by the movement of piston 3, the cool fuel flows through bore 23, cylinder 2 and from there through valves 5 and 8.. When piston 3 stops, it opens valve 7 and the remainder of the fuel passes through bore 23 as a cooling medium and then through check valve 7.

Upon refilling cylinder 2 with low pressure fuel, the high pressure fuel to chamber 20 and passage 21 is shut off and only a small amount of high pressure fuel from line 200 goes through passage 19 and bore 22. Also the fuel flows through the bore 23 when piston 3 moves from the left to the right, and the rest of the fuel flows through passage 17, bore 24 and passage 18 to low pressure line 100. The flow of cooling fuel is determined by the fuel pressure in front of or behind piston 3 during the filling and discharging of cylinder 2.

The size and position of circumferential groove 25 determines the time the fuel is emitted from the nozzle 5b and is ignited by the flame coming through the turbine from the engine combustion chamber 80, as well as the duration of the time the flame burns while passing through the turbine. It always prevents the flame from the engine combustion chamber 8c from burning too long or burning the turbine wheels or that unburned fuel is discharged from the nozzle b because of the late arrival of the flame coming through the turbine.

In FIGURE 1, the piston 3 is in a position in which cylinder 2 is filled with the fuel to be forced to the afterburner. For discharging the fuel and forcing it to the afterburner, a control pressure is exerted on the side of piston 13 which faces the piston 10 either manually or otherwise so that piston 13 moves to the right and high pressure fuel in passage 19 causes piston 10 to follow the movement of piston 13 while at the same time opening valve 11. Passages 17 and 18 are then closed off by piston 10 and high pressure fuel flows into chamber 20. From there the high pressure fuel flows through passage 21 on the second side of piston 3. The piston 3 is forced to the left and the fuel in the chamber opens valve 5 and flows to the afterburner 5c. An annular groove 25 in the piston skirt 3a communicates with the first side of the piston through bore 26 and, when the annular groove is aligned with valve 8, supplies fuel to the fuel nozzle in the turbine engine combustion chamber only after fuel has been supplied through valve 5 to the afterburner. In this instance, care must be taken that no unburned fuel flows out of the fuel nozzle in the afterburner tube. On the other hand, the valve 8 will be closed by moving of the piston 3 by the time the fuel supplied to the afterburner through valve 5 is ignited.

As piston 3 approaches the end of the cylinder 2 containing valve 5, then sufiicient fuel has been delivered to the afterburner to ensure ignition. Piston 3 then strikes valve 7 so that the remainder of the fuel in the cylinder completely flows out of the cylinder into the low pressure fuel line of the engine so that a suction can be created in the cylinder during the next intake stroke and as shown in FIGURE 2, while the afterburner continues to burn automatically with the fuel which has been supplied to it.

The control pressure on piston 13 is then released in order to refill cylinder 2 with fuel. Spring pushes piston 13 to the left and opens passages 17 and 18. High pressure fuel line 200 is closed by the seating of valve 11. Pressure is thus taken off of spring 4 which expands to move piston 3 to the right, and this intake stroke draws fuel from the low pressure line 100 from valve 6 into cylinder 2. The pump is then in the position shown in FIGURE 1 and is ready for another supply of fuel to the afterburner. The cross-section of the low pressure line 100 leading to valve 6 can be made of such size with respect to the size of the opening of valve 6 as to refill cylinder 2 in a very short time.

Bores 22, 23 and 24 permit sufficient fuel to flow from the high pressure fuel line 200 as to adequately cool the pump at all times.

In addition to the advantage of the short fuel filling time, this invention has the advantage of being extremely simple because no sealing seat is required which would have to be designed for an absolute seal. To the contrary, it is desired that a certain steady flow of fuel moves through the pump and, in particular, through the bores 22, 23 and 24 for cooling the pump in order that they can be installed adjacent the hottest engine points and thus short pipe lines used. Because the housing 1 is divided into several portions, as, for example, the cylinder end containing Valves 5, 6 and 7, the block containing passages 17 and 18, and the block containing piston 13, the pump can be adapted for supplying different amounts of fuel to the engine. When the amount of fuel is to be changed, it is only necessary to exchange the cylinder 2 and the piston 3 with corresponding parts of different size. The pump, for this purpose, can also, because the pipe lines are connected to the outside of the housing, be placed on the engine at an engine inspection point.

Having now described the means by which the objects of the invention are obtained, I claim:

An afterburner ignition system for a turbine jet engine comprising a main fuel supply in a main combustion chamber, a turbine, an afterburner fuel supply in an afterburner, a first igniting fuel nozzle in the main combustion chamber in advance of the turbine, a second pilot burner fuel nozzle in the ignition zone for the afterburner fuel supply, and a fuel metering device for feeding fuel to the first fuel nozzle and the second fuel nozzle;

said device comprising a cylinder, a piston having a skirt slidable in said cylinder, spring means for urging said piston toward one end of said cylinder, high pressure fuel supply means joined to said cylinder for forcing said piston toward the opposite end of said cylinder, low pressure fuel supply means joined to said cylinder for feeding fuel into said opposite end of said cylinder, low pressure pipe line means joined between said opposite end of said cylinder and said second nozzle for feeding fuel to said second nozzle, a circumferential groove in the piston skirt, a bore extending through said skirt from said groove, and check valve means in the wall of the cylinder connected to said first fuel nozzle for the flow of low pressure fuel from said cylinder to said first fuel nozzle when said piston is moved by the high pressure fuel supply means to align said bore and groove with said check valve means and after fuel has been fed to said second fuel nozzle, and then to shut off the fuel to said first fuel nozzle upon further piston movement.

References Cited by the Examiner UNITED STATES PATENTS 1,128,643 2/1915 Wetmore 103-2 2,360,093 10/1944 Ainslie et al. 103-2 2,804,241 8/1957 McDowall et al. 6035.6 X 2,899,798 8/1959 Broders et al. 6035.6 3,062,005 11/1962 Davies et al. 6035.6 3,141,298 7/1964 Simpson et al 6039.28

FOREIGN PATENTS 20,995 9/1909 Great Britain. 833,880 5/1960 Great Britain.

JULIUS E. WEST, Primary Examiner. 

